The invention relates to a gas-injection valve for injecting a gaseous fuel, particularly hydrogen, into the combustion chamber of an internal combustion engine.
Such a gas-injection valve is disclosed in German Offenlegungsschrift No. 3,541,484 as comprising a valve housing and, disposed therein, a piston which is guided so as to be longitudinally displaceable against a spring action and has connected thereto a needle valve by means pin. The piston separates a fuel-filled pressure-gas space from a pressure oil-filled operating space of the hydraulics control. The pressure-gas space is connected, through an exposed line and through bores in the valve housing, to a pressure space surrounding the pressure shoulder of the needle valve. The control-oil pressure and the gas pressure in the whole system are equal between injecting operations, and the closing spring acting upon the piston presses the needle valve against its valve seat. Thus, the closing force acting upon the needle valve is supplied solely by the closing spring.
As a pressure pump begins to operate, the pressure within the operating space of the control hydraulics rises, and the piston is displaced against the action of the closing spring while, at the same time, the gas pressure increases. As soon as the opening pressure of the needle valve is reached in the pressure-gas space, pressure gas flows through an orifice into the combustion chamber of the internal combustion engine.
German Offenlegungsschrift No. 2,038,097 likewise discloses, with particular reference to FIG. 3 and page 9 thereof, a gas-inject ion valve for injecting a gaseous fuel, one which comprises a valve housing and, disposed therein, a longitudinally displaceable piston and a valve element for controlling an injection port. With this design, the mixture flowing into the combustion chamber serves also as the pressure medium for operating the valve element which is designed as a poppet valve. However, there may also be provided an additional pressure medium for acting upon a piston on the valve element so as to assist in opening the valve. The valve is restored to its initial posit ion by spring action.
The present invent ion has for its principal object to provide a gas-injection valve of the type disclosed in German Offenlegungsschrift No. 2,038,097, but one which is simpler with respect to its valve-closing function and, furthermore, will allow smaller gas quantities to be injected.